A Singular Song
by hunterofartemis080
Summary: When they escape the Time War, the Doctor and his sister, the Singer, decide to try staying together. And that makes all the difference. Master/OC. Time Lady. Songs of TARDISes AU
1. Chapter 1

Iota Xi was underneath the console of her older brother's TARDIS as he regenerated. Her only brother.

No. Braxiatel would always be her brother, even if he was dead. Even if everyone was dead.

The planet was gone. Everyone was gone.

By the time that Iota pulled herself back up through the grating that had appeared in the new background her brother's TARDIS had changed to, he and his new face were standing with his back to her. "Theta?" she asked him, laughing slightly.

He turned to look at her. "Hello, Iota." His eyes were sad. She would have expected nothing but from a man who'd just destroyed his planet. After all, even if Iota had been there, even if she had helped, it had mainly been him. She'd merely been an observer, a supporter. A bystander.

She pulled herself up properly and walked closer to him. "You regenerated," she informed him, reaching out to rub the small amount of hair he had. "I don't like the hair. Too short. And the ears are too big." The comment made Theta smile.

"Were you having fun beneath the console?" He moved to lean against the main console.

"Quite a lot. I've never actually been inside this TARDIS background before." She nearly smiled, but her face fell just as quickly. She couldn't just ignore what they had done, as much as she wished they could talk about anything else. "We didn't get Koschei out." She had made him promise, as they stood there looking down at the Moment, that they would get Koschei out first.

Theta nodded. "I know, he said softly.

She leaned against her own section of the console, breathing heavily. "I promised," she whispered. "I promised myself I'd get him out before everyone died."

Theta pulled her into his arms, holding her. "I know. I'm sorry."

Iota let him hold her for a long while before she finally stepped away, looking up at him. "I don't know what to do now." She hated how broken the statement made her voice. "I don't want to be one of the last without him being with me." It didn't matter that she'd been doubting their relationship and why she'd ever stayed with him and had been considering divorce. She still loved Koschei and she always had. Now he was gone forever and she'd failed to save him and it was her fault.

Gently, Theta took her hands. "Stay with me. I don't want to lose you too."

"I don't want to be alone." She felt a few tears and was so thankful to see the same in her brother.

"You aren't alone. I'm here and I'm not leaving. You never have to be alone. I'm not going to abandon you again."

Theta could never know how much that statement truly meant to her.

"We would fight. We would have to separate eventually."

He shrugged. "We're both adults now. Mature. We can make it work."

She squeezed his hands tighter. "Are you sure, Theta Sigma? You want your little sister with you?"

"I would never want anything else, Iota Xi."

And she nearly smiled.

-VII-

It was a few days later that Iota walked into the TARDIS console to find every single mirror or smashable reflective surface destroyed. She froze, hands part of the way into pulling up her hair, and looked for any sign of her brother. They'd stayed apart for the last few days, leaving his TARDIS somewhere safe, so that they could begin to process their grief separately.

"Theta?" she called out carefully. "Are you there?"

"Over here." His voice was nearly silent. Iota followed it. Her brother was sitting on the ramp from the door, head in his hands.

"Are you alright?"

He wiggled his fingers. Iota had the sense that he'd smashed everything with his fists. "There was enough regeneration energy left to heal the injuries."

She crouched in front of him, making her brother look at him. "Why?"

"I don't want to see my face anymore."

"Why?"

His head hung again. "All of the children. I don't even know..."

"The war needed to be ended. Gallifrey was doomed."

"But the children..."

"I know." She sat down properly, leaning opposite her brother. "I know." She wrapped her arms around her pulled close legs. "I hate myself for surviving. Why am I the one who was able to escape? Out of everyone, out of the entire planet, out of all of the people, why was it me? Why was it you?"

He could only shake his head. "I don't know."

"There are so many people that I was never able to say goodbye to. I left the TARDIS farms with so much anger, I don't even know who..." Her voice caught.

"I know." He looked up at her again. "He wasn't the Doctor." She knew who he meant. "This is my ninth body."

A lie. But Iota knew why. She wished she could repress the regenerations that fought in the war. The regeneration that left the TARDIS farms instead of trying to protect the TARDISes. But she couldn't. Her regenerations were too loud. They'd always been too loud.

Iota closed her eyes and focused on her brother's TARDIS's song. It was beautiful and old and the only song left in the universe.

Neither sibling spoke again as they sat there, but they didn't need to.

-VII-

It occurred to Iota a little bit later that she could count the number of times she'd traveled off Gallifrey on one hand. There had been the first trip to a birth of a star a little after her first ever time at the TARDIS farms. There had been the trip to save the Zouti at a little over a hundred. There had been the trip to Earth when she was around three hundred and thirty. There had been the planet that Theta and Koschei had brought her to in their final years at the Academy, one she'd named randomly one night as they'd sat looking at the stars. And a final trip to a star birth.

Five trips. And now she was here, with her brother, in his TARDIS, a man who loved to travel beyond everything else.

She couldn't decide if she hated him or not for completely abandoning her. She was angry, definitely, but he was all she had left. She couldn't stay angry forever.

She wanted to. Oh, Iota really wanted to.

But hating him, the more that she thought about it, seemed so little after the war. So childish. After everything he'd done and everything she'd been through, how could she hate him for not visiting his little sister?

"I want to see a planet," Iota told her brother, entering the console room. While she wandered his TARDIS, listening to the song and finding places that required healing, her brother stayed mostly in the console room. It was easier for him there, it seemed. Iota didn't dream of forcing him to leave it.

He looked shocked. "Really? Any one in particular?"

"I don't know." She ran a hand along the console as she passed it. "I never had a reason to consider it." She stopped in front of her brother. "Show me the reason that you two left Gallifrey."

"It's not that simple."

"Then begin to try. We're all the other has left, Theta. I want to...I want to understand." She watched his expression. "If you're ready, that is."

He was quiet for a moment. "I think I am. Something small."

She nodded. "We have to move slow. Ensure that we won't hate each other."

"That's quite a lofty thing to attempt." He moved, reaching out a hand for the console, and paused. "Help me pilot."

Iota raised her eyebrows. "Why don't you help me pilot? I am the one who was in the TARDIS farms."

"Healing them. Not piloting them. Key difference."

She mimed exaggerated listening, cupping a hand behind her ear. "Your TARDIS agrees with me."

"You can't know that."

"I'm the one with a bond to TARDISes." She flicked her hands at her brother. "Now, let me pilot. You pick the location. I will steer."

Thankfully, Theta did not debate that further. Iota almost wished he would. Everything would be better if he pushed it further. It would be normal if he pushed it. They were siblings. Every time they spent extended time together, they argued. They needed to argue to be normal.

Without arguing, it felt like they were ignoring the problem. Hiding from it. Pretending that it wasn't there. Iota wished that were possible, effective, but she knew it wasn't. As much as she hated to admit it, she knew that avoiding a problem didn't make it go away.

She'd tried, on Gallifrey, in the Academy. Every moment she'd been confronted she'd tried to avoid the problem. Even now, after the war, she'd considered...she wouldn't think of that anymore. She couldn't.

But it was still so appealing.

The journey was rougher than the other flights Iota had worked on. Iota knew that was because, like Theta had said, she'd been healing TARDISes, not piloting, so she was a bit out of practice, but she refused to tell that to her brother.

She wished he would mention it again. They would be normal if he mentioned it again. Like they were on Gallifrey, when their greatest worry was a test or a friend. When they could just run through the grass and be together and be happy.

Not anymore. No more.

They stayed still a moment, even after the TARDIS had landed. Theta seemed to be waiting for Iota to decide that she didn't want to do this, that she didn't want to see exactly what had pulled her brother and husband away from her. She did know, at least in theory. She'd known both of them for centuries, after all. She'd heard all of their dreams of seeing the universe, of bouncing among the stars.

What she didn't understand, what she wanted to understand, was why that pull had been so strong that they'd forgotten about her. Or, if they hadn't forgotten about her, why they'd never come back.

There had to be something out there, in the universe, that had pulled them. That had to be what it was. Iota had to believe that.

And now she would be able to see it and maybe she'd be able to lose herself in that and forget that her entire planet had been turned to dust by her brother with her help.

Iota went to the door. Her brother followed close behind. She did pause, one hand on the door, taking a breath, before she opened it.

This was her life now. This was all that was left. They were all that was left.

When she opened the TARDIS door, Iota expected a planet surface. A new sky. People that Theta had abandoned her to walk among.

Instead, she found stars.

Different stars, stars she didn't recognize from Gallifrey. Stars that looked like they belonged to an entirely other universe.

"This," Theta said, stopping at Iota's side, "is why we left Gallifrey."

"There are stars on Gallifrey."

"Not like these." Theta pointed at a cluster. "Remember the planet that we took you too, back at the end of the Academy?"

It looked so small from here. "I remember." She remembered those one-inch tall creatures, wandering a planet filled with two hundred foot trees, sky yellow and streaked red above them. "You just wanted to see the universe."

"We'd planned to see them together, me and him."

"I remember."

Iota always would.

 **A/N: I always did wonder what would happen if Iota stayed with her brother after the Time War. Now we have a chance to find out ;)**

 **In case you need a refresher, this regeneration of Iota, her seventh, resembles Alexandra Moen.**


	2. Chapter 2

When Iota and Theta ended up on Earth in Southhampton in 1912, it was not intentional. They'd been aiming for a concert in the twenty-second century that Theta had known Iota would enjoy. Her brother had set the destination and though Iota had piloted, somehow he still managed to mess it up.

"Well," Theta said, being the first to go to look out the door, "I think one of us has messed up."

"One of us?" Iota pulled up the screen with their actual location. "I do believe this was entirely your fault."

"All I did was set the destination."

"And our destination is what is wrong. The piloting was perfect." Iota turned to her brother, who'd yet to turn around. "What's wrong now?"

He looked over his shoulder. "There's a child."

Iota couldn't tell if she was surprised or not when her immediate reaction was to grimace. Even if she'd bonded with some children – primarily Cla'ron, though there had also been the young boy from Arcadia, Kari – she still did not like the majority of children.

And then Iota winced again as she remembered how she'd reacted to Theta's son, Alpha. She'd never properly apologized though, granted, Theta also needed to apologize about the fact she hadn't been told about Alpha's birth.

"Who are you?" Iota heard the child speak. She understood him to be speaking English, though Iota heard it as Gallifreyan. The TARDIS was responsible for that. Iota supposed she would have to start practicing other languages again. Theta's TARDIS would help most of the time, but it would be easier to translate herself. "How did you get here?"

Theta poked his head more out of the TARDIS. "Ah, yes, we seem to have landed in your bedroom." Her brother spoke English. The accent those words gained shocked her. It was similar to when he spoke Gallifreyan, but there was something different.

Iota wondered what accent humans would identify her with when she spoke their languages.

"What's your name?"

"Marcus Anthony James Daniels." The boy recited his name like he'd practiced.

' _Do you want to leave?'_ Theta's voice tugged at Iota's mind so lightly that it shocked her. It had been so long since they'd used their mental bond she'd almost begun to wonder if they'd lost it. But it was there, if faint.

She was glad she didn't have to walk down the tree of Time Lord consciousness. She didn't know if she'd have been able to stand seeing only one other Time Lord along it.

' _Do you want to?'_

Theta's smile drifted along as well. _'Let's just put the boy back to bed.'_

Iota moved away from the console. Her brother stepped out and knelt down to the boy's height. He was very young. "Marcus, my name is the Doctor. This is my sister, the Singer. We're just passing sandmen, coming to give you some good dreams."

Marcus crossed his arms. "I wasn't having good dreams."

"I'm very sorry about that. We got stuck up at the next house over. There was a little girl there who was trying to stay up late reading. She was very determined."

"Genny says that sandmen aren't real."

"Well, Genny's silly." Theta nodded back at the boy's bed. "Now, why don't we get you back to bed? Sis and I have got more children to visit, more good dreams to spread."

"Mummy always sings to help me to sleep."

Theta glanced back at Iota. "Well, then it's very good that my sister has a beautiful singing voice."

' _I haven't sung in this regeneration yet.'_

' _I'm confident that you can still do it.'_

Iota forced a smile for Marcus, though the boy seemed to understand that it wasn't entirely real since he didn't match it. "I would be happy to sing for you, Marcus." The English made her tongue feel stiff. The words felt like the language looked, insects marching through her mouth. "Is there any song you would like?"

"A lullaby."

' _Do you know any Earth lullabies?'_ Theta asked her as the boy turned, moving back to his bed.

' _I used to. Can the TARDIS translate for him?'_

' _Why do you ask?'_

Iota's smile became real than, for a moment. _'I know Italian ones.'_

' _Of course you do. But the TARDIS should translate.'_

Iota took the seat next to the boy's bed, no doubt used by his mother for this same task. She was thankful the boy could tuck himself in. She didn't know how to do that. She'd never had to before.

"Are you all settled?" she asked him, gripping her hands on her lap. Anthony nodded. "Then I will begin."

Iota didn't know many Earth lullabies, not even Italian, but she did remember one. 'Brilla, Brilla La Stellina'.

The song worked for Marcus and, before Iota had even finished, he'd fallen back asleep. Iota stood and moved back carefully to where Theta waited.

' _It worked.'_

Theta smiled at her. _'It was beautiful. I knew you'd be able to do it.'_ He'd been about to say something else when his attention, making him turn. _'Iota...'_

' _What is it?'_

Theta lifted a small piece of paper and handed it to Iota. She was thankful for the TARDIS and its translation. _'I don't understand.'_ The paper was some sort of ticket for a ship called 'Titanic'. _'I don't recognize it.'_

' _It's a human ship. They claimed it would never sink, but it hit an iceberg. And it did. More than 1,500 people died. And that is a ticket for it. This boy and his family are going to go on it.'_

' _Perhaps they'll survive.'_

' _Only 706 people survived._ _'_

She frowned. _'You want to stop them from going on the boat, don't you?'_

' _Marcus might die if they go on the boat.'_

' _What gives you the right to save them?'_

' _All of the children of Gallifrey.'_ Theta looked down. _'I need to make up for all of the lives I took. All of those innocents.'_

Iota looked back to Marcus, curled into himself in sleep. She'd never had to save someone before, not really. She'd never even considered doing that though, she supposed, she'd never had the chance to. Her brother had traveled the universe and gotten notoriety, both on Gallifrey and off, for interfering. But Iota had no problems with interfering – that wasn't her problem with her brother. She knew there were some things that needed to be stopped and some places that needed to be saved.

She'd just never had to do it herself.

But now she and her brother were the last Time Lords. Why would that mean they stopped trying to save people?

Especially when they were responsible for the destruction of their people.

' _How do we save him?'_

Theta smiled. _'We have to find his parents. Become close. Convince them of the danger.'_

Iota looked out the boy's window. _'It's the middle of the night. If I remember rightly, humans, even adult ones, are asleep now.'_

' _We can either wait or pilot the TARDIS to the morning.'_

' _If I can set the destination, we can pilot.'_

' _It wasn't my fault!'_ but Theta still stepped to the side, letting Iota be the first back into the TARDIS and up to the console.

It was more difficult than she expected to merely pilot the TARDIS a few hours forward in Earth's relative timeline. It was very specific, required a careful hand.

But Iota succeeded. She checked on the screen and couldn't help but smile when the success was evident.

"Should we change our clothing?" Iota asked, turning to look at Theta. "The one time I traveled to Earth, we had to dress to match the times. Is it necessary?"

He shrugged. "Not necessary but helpful."

"And your TARDIS has clothing fit for 1912 Earth?" Iota had been inside her brother's closet before, to change out of her armor, but she hadn't seen anything beyond what she'd recognized as late 20th, early 21st century Earth fashion. She'd put that down to that clothing being from where her brother spent the most time.

"She has clothing fit for everywhere."

-VII-

Theta was proven correct, though Iota had never actually doubted him. When the siblings emerged, they were both dressed in clothing that allowed them to properly blend in with the humans around them.

Iota had gone with a traditional gown from the period in a shade of deep red. Originally, she'd avoided the color entirely, but it drew her too much. Though the color reminded her of Gallifrey and the fields she'd adored, it was more comforting than upsetting.

But she still wore black to mourn the loss of Gallifrey. She was one of the last. It was her responsibility to remember.

There was the black ribbon on her wrist for a friend. A black sash, worn as the belt below the bust of the gown, for a sibling. A shawl for the parents. And a hat for the spouse. Technically, according to Theta, who knew more of these things than Iota, they should have avoided all social events until the end of the current regeneration, but saving a family from the doom of the Titanic did not truly count as a social event. And most Time Lords skirted that requirement.

When they emerged from the TARDIS, Iota was reminded exactly why she'd changed to primarily wearing TARDIS farm jumpsuits. In her youth, she hadn't had anything against robes beyond later developing a dislike of having her collars too high, but over the centuries in the TARDIS farms – she didn't know how long – she'd decided that she didn't actually like robes. Which now translated into not liking human dresses.

She would have to examine the TARDIS's closet more after they were finished. The skirt and blouse she'd picked before they'd gone to end the Time War were nice, but they didn't feel right. She'd picked them because of their similarity to what she'd worn the only other time she'd gone to Earth.

She wanted to find something better for this regeneration. Something that made her feel better despite her loss.

Something red.

"We'll need names," Theta said, holding out his arm for Iota to take as they moved to the edge of the street. They'd landed the TARDIS outside of the home that they'd landed in, the TARDIS's shape standing out in early twentieth century England. "Second names or titles won't work on their own if we're trying to blend in in any regard."

"Lucy," Iota said immediately, remembering the name that she'd picked centuries before, though she didn't remember exactly why or when. It wasn't a common thing for Time Lords to also pick human names for themselves.

"Lucy Smith?"

"Why Smith?"

"I'll me Dr. John Smith. You're my sister. Humans have family names."

Iota frowned. "But I'm married. If I remember human society rightly, I would have taken my partner's name."

"He never had a human name. Not a consistent one."

"Then I will be Lucy Cole." The full name she'd picked so long ago. Cole would be their family name. She thought Koschei would have liked it.

Theta nodded and without another word the siblings moved across the street. Iota trusted Theta's experience to give them a realistic story to convince the Daniels to let them inside. And to convince them to cancel their tickets for the Titanic.

She was the one to knock. There was a shimmer of Theta's confidence, drifting across their mental bond. It helped her straighten her back.

Iota had never been someone who had difficulty with confidence in any regeneration, but after the war, after everything she'd done and seen...she needed a little help. But she would be back to normal soon.

She had her brother's help and they would help each other.

 **A/N: Needed to touch on at least one of the solo adventures we know the 9th Doctor went on before Rose ;)**

 **Notes on reviews:**

 _Purplestan: Honestly, I missed her too, though it did take some adjusting since it's been so long since I've thought about what the Singer was like before the Saxon adventures._

 _Mermaid1108: So glad to hear that! :)_

 _Guest: Those episodes will definitely be...interesting ;)_


	3. Chapter 3

Somehow, Theta had convinced Mr. Daniels, named Anthony, that the two of them had been school friends. Iota still wasn't quite certain how he'd done that, or how it had been at all effective. But he had, and now he and Iota were sitting in the Daniels' sitting room, Mr. and Mrs. Daniels opposite them, drinking tea.

Iota had never tried human tea before. Gallifrey had a similar drink made of hot water and dried plants, but the flavor profile was distinctly different. She'd managed to keep the initial grimace off her face as she adjusted to the taste, though Theta recognized it through their mental bond.

"Tell me of yourself, Lucy," Mrs. Daniels, named Alice, asked Iota. "I always find sisters more interesting than their brothers."

"I'm afraid I have nothing interesting to impart." Iota felt she could hear her own accent. She was careful to make it match Theta's own. She presumed human accents worked at least similarly to Gallifreyan ones, with families raised together maintaining similar ones. "I was married, once, but my husband..." she glanced at Theta and had an idea, "he died in a boat sinking."

Alice frowned. "I'm so sorry, Lucy. That is so tragic."

Iota hated using Koschei and her grief to save humans, but it could be effective. At least, she hoped it would.

"Yes. It is why I am with my brother now. He is helping me in my grief." Not a lie. Theta reached out to take Iota's hand, smiling. "The boat was deemed unsinkable. No one expected it to sink."

"All the more tragic."

A boy, whom Iota and Theta recognized, ran into the room and stopped at the sight of the strangers. It was clear by the way his eyes widened that he recognized them as well. "You were in my dream last night."

Theta turned to face the boy properly. "Well, are you a psychic? Because it seems you've seen the future."

Young Marcus crossed his arms. "I'm no psychic."

"This is Dr. John Smith and his sister, Mrs. Lucy Cole," Alice explained, gesturing to the boy. "Dr. Smith was a friend of your father's at school. They have come to visit."

Anthony looked at Theta. "It's very good that you came now. You're just before we've truly begun to prepare for our journey to the new world."

Theta frowned. Iota felt that he could have been an actor. "Journey for the new world? On what ship?"

"The _RMS Titanic_."

Iota widened her eyes, pressing a hand to her mouth. "Oh, but you can't! Please, you mustn't!"

Theta took Iota's hand again. "Lucy, they will be fine. You needn't worry."

"It is called unsinkable, but Harold's boat was unsinkable." She looked to Mr. and Mrs. Daniels again. "Please, you mustn't, for my sake, if not your own."

"Lucy, please, not in front of the boy." Theta nodded at the child before looking back to the parents. "I am so sorry about this. Lucy believes herself capable of sensing when tragedy will strike. She has been this way since childhood."

The Daniels' exchanged a look. "What makes you believe tragedy will strike the boat?"

"Boats are not unsinkable." Iota stood, moving to take Alice's hands. "Please, I will pay for new tickets for your entire family on any other boat, however expensive. Just, please, do not go on the _Titanic._ "

Marcus rushed to his mother's side. He looked afraid. That hadn't been Iota's intention but, she supposed, it would be even more effective than the sister of a school friend the man didn't even properly remember. "I don't want to go on the _Titanic_!" he cried, gripping onto his mother's skirts.

"Marcus, darling, it will be fine," Alice said, running a hand down the back of his head.

"I don't want to go!" He turned his gaze up to his mother and wrinkled his nose. Iota was reminded of one of many reasons she disliked children, particularly those of his age.

"I'm sorry, Marcus, but we cannot just cancel our tickets," Anthony said, trying to smile at his son. "I understand that what Mrs. Cole said was frightening, but she cannot know the future."

"I'm not going to go." Marcus turned and rushed to Iota's skirts. "Please, Mrs. Cole, convince them not to go. I don't want to die."

Iota looked up to their parents. "Please, just take another boat. Any other boat. Just not the _Titanic._ "

The Daniels' exchanged a look. Iota saw their discomfort. Their unease. Humans were terrible at hiding it. "Perhaps..."

"Please," she begged, eyes wider. "Just not the _Titanic._ "

"Another boat."

Iota shared Theta's relief as it rushed towards her.

A few lives to begin to make up for hundreds. Thousands. Millions. An entire planet of innocents.

And a family, saved.

-VII-

Iota and Theta stayed with the Daniels family until the new day they were meant to sail. They met the Daniels's two daughters and the eldest, the one Marcus called Genny, taught her how to play an Earth piano.

And four days after the _Titanic_ had set sail, it hit an iceberg.

When the Daniels family heard that truth, they stood, frozen, and then turned to Iota.

Theta pretended at shock. But Iota knew he was proud.

The Daniels insisted that Iota and Theta take a picture with their family to honor the fact that they – Iota – had saved the Daniels' life.

As soon as they could, Iota and Theta found a reason to leave the Daniels. Once they were back inside Theta's TARDIS, Iota fell back against the closed door, hand on her chest, breathing hard.

Theta turned in a circle, smiling, for once. "We saved them." He stopped and looked at Iota. "Together."

Iota felt like laughing, even if she didn't. Maybe she would have if she hadn't just used her husband's death to save them. She couldn't just ignore that. "Together." She touched where Koschei's ring hung around her neck. "I need to get out of this dress."

Theta laughed again. "At least it doesn't have a high collar."

"Thankfully." She pushed herself off of the door. "You're going to need to help me out of it."

Theta didn't fight that. The siblings walked back through his TARDIS together.

"So, do you do things like that often?" Iota asked him. "Rescue innocents? Is this what you left Gallifrey for?"

"I aim for it. Most of the time." He shrugged. "The most important thing is always stopping something dangerous from happening if it is. That helps to save people."

Iota touched the ring again. "And the person you're stopping has been Koschei. Multiple times."

"Yes."

"We'll have to find someone dangerous to stop. I want to know how that feels."

Theta smiled, though it was pained. "That won't be difficult. The universe is full of people trying to hurt each other."

"Is that really why you went out to the universe?"

Theta shook his head. "I went out to see it. Saving people, stopping evil...I never meant to do that. It was incidental."

Iota didn't know if she quite believed that, but she stayed quiet. They reached the closet and Theta helped Iota out of her dress as quickly as possible before the siblings separated.

Theta knew how to pick clothing for a regeneration. He'd already done it for this new one, having appeared in a tee-shirt and jacket shortly after his original regeneration. Iota had stayed in the skirt and blouse she'd first picked, even as it had grown more uncomfortable.

Even on Gallifrey, when she'd regenerated, she'd just stayed in the same clothing as a previous regeneration. She'd just been in Academy robes and then transitioned to TARDIS farms jumpsuit. Clothing had never been something distinct to a regeneration, not like it was for most other Time Lords, even when they were just limited to robes.

But now she couldn't just wear a jumpsuit.

Iota moved through Theta's collection of clothing and was impressed to see exactly how much female clothing there was...and then grimaced because she realized how many women it meant had passed through his TARDIS.

She made a note to have him tell her about the majority of them. It felt important.

As she hit clothing she liked, she pulled it out and laid it down. Thankfully, she didn't end up with much.

She wished Nella could have been there, or anyone else. Anyone from her family, her planet. If she had any interest in clothing, it could have been an activity she enjoyed on her own. But Iota had never cared that much, not really.

In the end, Iota had a red shirt, tight but flexible black pants, boots that seemed designed to be toughened, and a black jacket. It was strange to be dressed in so much black when she'd always mainly worn red, but it was necessary. She needed to respect all of the people she'd lost. She needed to remember them.

The final step was Koschei's ring. It still hung around her neck as it had during the war.

He'd given it to her to promise that he would Merge with her in the future. But now he was dead. Now he never could. Now the ring only symbolized a promise that could never, would never come to pass.

And yet it was all she had left of him. If she got rid of it or stopped wearing it, it would be like getting rid of him. She wouldn't do that.

Iota kept the ring on the necklace, but she let it hang out. Soon, she'd be able to wear it properly, but, for now, she'd rather keep it safe around her neck.

When Iota returned to the main console room and her brother, he smiled at her. "You look far more comfortable now."

"Thank you." She brushed a hand through her hair. She'd tied a ribbon around her wrist as well, planning on using it to pull her hair back whenever she needed to. "I feel better."

"That's good." His gaze fell to the necklace and Iota wondered if he'd ever seen it properly before. If he'd ever considered it before, really considered it. He had seen it the few times he'd seen her on Gallifrey before he'd left, though those times had been arguments, not chances for Theta to study her limited jewelry. "What is that?"

"It's from Koschei. A symbol of his promise to Merge."

Theta swallowed. "You really don't know who he was, do you?"

"The High Council wanted me to divorce him. It was easy to gather what that means." She moved closer. "During the War, they called me the sister of a criminal and the wife of a madman. Everyone knows who the two of you were."

"And you still wear his ring."

"Koschei is still my husband, no matter what he may have done. I never divorced him."

"Do you still love him?"

"I..." Iota looked down. "I don't know." And that was the truth, no matter how painful it was to vocalize. She'd loved him once, loved him more than anything in the universe, and then...then he'd left. Then he'd refused to come back. Then he'd become a madman.

"That's okay," Theta said, moving forward to take her hand. "You don't have to know right now. You have time."

Iota hugged her brother tightly then. She'd always been someone who loved hugs. Thankfully, Theta was still wonderful at giving them.

She had time to figure out how she felt about Koschei. She had as long as it took. As long as she needed. Koschei was gone. She didn't have to worry about potentially confronting him ever again.

"Do you want me to fix it?" Iota asked, still hugging her brother.

"Fix what?"

"The chameleon circuit."

"Never."

And Iota laughed.

 **A/N: They saved a family! And even got some good sibling bonding in as well :)**

 **Notes on reviews:**

 _Purplestan: The two will definitely have a better relationship after traveling together for a bit. And the Master will definitely be...interesting ;)_


	4. Chapter 4

Iota frowned at a switch on the TARDIS console. It was stuck and it was not clear if that was because of some technical difficulty or just because Theta had gotten something stuck under it. She focused on his TARDIS's song – it was distant, but it was there. Much better than it had ever been during the war.

When she focused, she could hear it perfectly, clearly. But she had to focus. In the TARDIS farms, on Gallifrey, TARDIS songs would drift in and out of her attention, swirling in a grand chorus that, after her first regeneration, was as natural as breathing. It was strange to need to consciously access it. It felt like her first regeneration again, when merely hearing one TARDIS song was enough to shock her into unconsciousness.

Thankfully, that didn't happen now. But it still wasn't as easy as she was used to.

As though it heard her and understood, the TARDIS song strengthened itself, comforting her in its power. She smiled despite herself.

The switch was stuck because of Theta. It was simple to pull up the panel and dislodge the item he'd gotten stuck there, which looked like a dried piece of Earth gum. Iota shook her head and made a note to mention to Theta that he could not stick gum into the TARDIS.

This was the last TARDIS in existence. They had to treat her carefully.

Iota moved back to search for a place to throw the gum, her free hand reaching to the ring still hanging around her neck. Since saving the Daniels, they hadn't left the TARDIS, with Theta off attempting to pick the next best place for him to show her. It seemed he wanted to ensure that the universe make a good impression on her.

Iota twisted the ring and pulled it into her line of sight, studying it in the light of the console. It was simple, rather small. A silver band with a vein of dark green down the middle. It barely even looked Gallifreyan. Nothing like his signet ring, which bore his family insignia. She wondered what had happened to that ring. If he'd still had it in his last breaths, or if he'd lost it, either before the war or during it.

She wished she'd been able to see him in the end. The last time Iota had seen her husband...she'd been in her second regeneration. He'd told her about how Theta had attempted to trap him in a black hole. They'd...she'd gotten pregnant after that. Iota blinked at that memory.

She'd forgotten. She'd forgotten the baby she hadn't known she'd ever wanted. The baby she'd lost in an explosion at the TARDIS farms.

Iota and Koschei had never wanted children. They were expected to have them, as two Time Lords who'd been in regenerations that could procreate for an extended time, but they hadn't been required to keep it. She hadn't even gotten far enough along to seriously consider what would happen to the child. To consider if she would have wanted to keep it, once she'd realized that Koschei was never going to come back to her, that he could never come back.

She wondered if she would have kept it then if only to have a piece of him to keep. It was easy to say that she would have, but then Iota remembered...that had been when the High Council had first offered divorce.

Iota moved forward again and brought up any records this TARDIS had of her husband. It was strange to type his title, to remember that he'd called himself the Master and not stayed the Koschei she'd first fallen in love with.

It was even stranger when she saw the first image.

She recognized the outline of his face, the grey eyes she'd first loved, but he had a...Koschei had a beard.

When had he gotten a beard? Why hadn't she known about it?

He'd been her husband, but Iota knew almost nothing about the man Koschei had become. And that terrified her.

She flicked through the other images, seeing each of his faces, every face she'd never seen, until she reached the records of her brother and his encounters. The rumors of what her husband had done to the universe.

By the time that Theta re-entered the console room, Iota was sobbing.

"Iota!" he said, terrified, and rushed forward, but he stilled when he saw what was on the screen.

"That's not..." Iota swallowed hard, gaze fixed on the final face that the records had shown, a burnt corpse that had been desperate for new regenerations, summoning Theta back to use him. She remembered when she'd heard that they were back on Gallifrey. Rikou had come running, telling her that there had been word that Theta and Koschei were back, that they were somehow involved with the Lord President. She remembered how she'd spent days waiting for them to come to her, for either of them, but they hadn't.

This was who she would have seen if Koschei had come to see her. This corpse, this dying thing. She would have had to face the truth of what the High Council had been telling her – Iota hadn't doubted them, not really, but she had tried.

"That's not Koschei," she finally finished. The TARDIS had no records of the boy from her childhood, but Iota remembered. "That's the Master."

It broke her to say that. Iota felt something shatter insider of her.

She'd spent so long fighting herself about if she still loved him or not. So long trying to decide if she could still love a man she hadn't seen for centuries, a man people kept telling her to divorce. She'd died in her fourth regeneration because she'd tried to hold onto a man who would never come back to her.

And now, she just said it. Made it real.

She didn't love the Master.

She almost thought she hated him.

"Do you still want to be married to him?"

"It doesn't matter. He's dead."

"But if he wasn't..."

Iota wished she was able to say that her answer would be the same. That she wouldn't have cared if she could walk out of the TARDIS and see him, touch him, know him...Iota knew it wouldn't be that simple then. No matter what she decided now, no matter what truth she learned, she didn't know what she would do if he was still alive somewhere.

Thankfully, she would never have to find out. Because he was dead.

Everyone was dead.

"It doesn't matter."

Theta touched her arm and Iota didn't flinch from him, though she had to fight to keep herself still. "Your feelings matter."

That time, she did flinch from him, turning. "Then why didn't you come back and see me?"

"I wanted to..."

"I waited for you. Every single time that I heard you were back on Gallifrey, I waited for you. And you never came."

"I'm sorry."

She shook her head. "Sorry is not enough. Why didn't you come?"

Theta took a deep breath. "We don't have to do this, Iota. We shouldn't do this."

"Why didn't you come?" Her fists were clenched at her sides and she almost wished for a weapon from the war just to make her brother finally tell her the truth. "Tell me, Theta Sigma."

"You never grew up." He whispered, but she heard him. "You refused to do anything with your life that could actually lead to something. You just wanted to stay. You just wanted everyone else to stay with you. And I couldn't..."

Iota blinked. "I never grew up?"

"Did you really think you had? You still call yourself Iota. You still call me Theta. You called him Koschei. We've all chosen our titles. There's no place for second names anymore."

Iota remembered when Koschei had seen her sucking her thumb. When he'd gotten angry and ordered her to stop, forbidden her from ever doing it again. When to apologize, he'd first given her the ring and promised to Merge.

They thought she was a child. The people who'd meant the most to her thought she was a child. Thought she was weak. Foolish. Immature.

They'd thought she wasn't worth coming back for.

"That's not good enough." She shook her head. "That's not enough of a reason to abandon your only sister. I died because you didn't come back. Because you didn't want to bother with me anymore."

Theta blinked. "You died?"

She nodded. "My fourth regeneration. When I heard you were on the planet, when you never came...I let my body fail. I wanted my hearts to stop. I didn't want to regenerate." Her voice had dropped to a whisper.

"Iota..."

"You didn't even say goodbye. Maybe, if you'd said goodbye..."

"I am so sorry." Iota didn't criticize that sentiment. "I'm sorry I left without saying anything. I never meant to hurt you like that. I never meant...I'm sorry."

Iota let the silence hang, one hand slowly running along the outer edge of Koschei's ring, before she spoke again. "Did you go to the TARDIS farms? Did you try to find me in the war?"

"No."

She nodded. She didn't know what she'd expected. Even when she'd heard of her brother in the war, even when she'd been aware of him somewhere nearby, she hadn't truly thought him saving her was an option. After so long of him not coming, she had never considered he would. And he hadn't, not really. He'd saved her because she'd been there and he'd recognized her and perhaps he'd felt guilty that he hadn't been there before.

Or perhaps he'd been confused and hurting and just wanted to save someone to atone for all of the deaths he'd been about to be responsible for.

"Do you know why he never came back?"

"No, I don't." Iota was glad that Theta didn't guess. "Though he was less welcome on Gallifrey than even I was. Perhaps he couldn't, even if he wanted to."

"Perhaps." And perhaps the High Council hadn't asked her to divorce him. Perhaps she hadn't had to ignore every sign that her husband was not the man she'd thought she was. Perhaps the dark-haired boy who'd run through red fields with her had never really gone away.

All they had now was perhaps. And that was nothing.

"I thought of somewhere we could go," Theta said as Iota's hand fell away from her ring. "Where there's something dangerous we can stop."

"Where?"

"Villengard." Theta looked towards the console and, at Iota's nod, stepped to it in order to bring up the necessary information. "They call it the Nightmare of the Seven Galaxies."

"And what would we be stopping?"

"A weapons factory."

Iota thought of all the death in the war. All the horrors on the planets the war had spread to, though she'd only ever been on Gallifrey. She'd still heard reports. Still known of massacres.

"Let's go visit Villengard."

 **A/N: A big moment of revelation for Iota, and an important change from the original story :)**

 **Notes on reviews:**

 _Purplestan: These two deserved something cute after the war :)_


	5. Chapter 5

Originally, Theta and Iota were not planning on destroying the Villengard factories entirely, merely disrupting production, but once they were there...the siblings agreed that it needed to be stopped. Theta went to the reactor in order to use it against the factory, hiding the destruction in what could look like an accident. For a moment, they'd considered Iota as the one who would do that, given her tendency to destroy any non-Gallifreyan technology, but they'd agreed that she would, somehow, manage to actually fix the reactor in her attempts to destroy it.

Instead, Iota was sent to look for shipping records so that they could find some of the weapons after the factory was gone. Before she found that, she found the storage for shipments. Iota had been about to leave, knowing these wouldn't matter once the factory was gone, when her gaze landed on a crate labeled 'sonic blaster'.

Despite herself, Iota's hand flexed.

She'd never felt strongly about weapons before the war. She'd never needed to. Weapons had no place in the Academy or the TARDIS farms, and those were the only places she'd spent time in. Since she'd never thought she'd ever leave Gallifrey, she'd never thought of facing people who would want to hurt her.

Until the war. And even then, Iota had not flinched from picking up a gun when it meant that she wouldn't be the one responsible for the destruction of TARDISes.

Slowly, she walked over to the crate and dug her nails into the lid, using the Gallifreyan strength that she never bothered to use to open it. The blasters inside were nothing like the guns she'd used during the war, but Iota didn't think she'd have been able to tolerate the exact same kind of weapon.

This blaster, though...Iota liked the weight of it in her hand. The way it made her back straighten because she could finally do something to hurt the things who'd hurt the people she cared about. She could finally protect herself.

And if she ever saw Koschei again – an impossibility, but it was a comforting thought – she would be able to shoot him where he stood before he got a word in edgewise.

Iota tested the weapon on the wall of the storage room and enjoyed how it made a hole for her to move through. She would have to discover the other settings. See how strong it actually was. See what changes she could make.

There was only one TARDIS left. Iota wanted to be able to fix things beyond that ship. She wanted to be the one who went to the reactor, who knew exactly what buttons to press and which gears to turn. To know every bit of technology as well as she knew the TARDIS.

To prove to everyone that she was not the child who hid in the TARDIS farms anymore.

-VII-

The siblings met back up at the TARDIS, Iota reaching where they'd left the ship by blasting a hole in the building wall shortly before the factory actually destroyed itself. Theta pulled her into the safety of the TARDIS before either of them was in any real damage.

But he stepped away quickly, focusing on the blaster in her hand. "What is that?"

"Apparently, a sonic blaster." Iota held it up. "Primarily, it seems to shoot holes in walls. Hopefully, it has other features."

"It's a weapon."

She nodded. "Yes, Theta, I'm aware of that. I fought in a war."

"So did I, but you don't see me holding a gun." He frowned. "We just destroyed a weapons factory and you ended up with a weapon? Don't you realize how terrible that is?"

"Don't worry, I'm aware enough to know that. But I feel safer."

"You shouldn't have to."

"I don't care if you're the only other Time Lord left. You still don't get to protect me. I can protect myself." She tightened her hold on the blaster. "And I am going to keep the blaster."

Theta wanted to fight it. Iota could see that in his eyes. He wanted to make her throw the blaster into the void because seeing it reminded him that she'd been a soldier and he'd been a soldier and they'd destroyed their planet and people. But Iota felt stronger with the weapon. Better. Safer.

"You have a sonic screwdriver. I have a sonic blaster. Now we're balanced." Iota turned, going back to the closet to find a strap to keep the blaster on her at all times. She was thankful Theta didn't try to stop her.

She managed to find a strap to hold the blaster to her outer upper thigh. She liked that it was there. She could always touch the blaster when it was there. Always remember that it was there and she was safe and strong and that no one, not even Koschei, could hurt her.

When she returned to the console, Theta was standing at it holding an Earth banana, which Iota only recognized from textbooks. Iota frowned at it, but he spoke first. "There's a banana grove there now. Where the factory was."

"Another balancing act."

He held out the banana to her. "Have you ever had one?"

She took it carefully, turning it around. "It's a fruit, isn't it?"

He nodded. "Bananas are good." She sniffed it. "You peel it."

Iota moved to do that, wondering at how much of the universe she had no knowledge of. She had really never cared about things beyond Gallifrey, not like her brother and Koschei had. She'd attended the lessons and passed the exams, but she'd never really known it. Never seen it.

And it wasn't even that, now, she wanted to. It wasn't like she'd unearthed some innate desire to see everything the universe had to offer. More...she just didn't want to be alone. She just wanted to understand everything her brother saw in the universe.

Then maybe, just maybe, he would begin to understand everything she saw too.

"Where to next?"

"You don't want to take a break?" he asked as she took a tentative bite of the fruit.

"Do you?" she made a face and gave the banana back. "I do not like bananas."

He laughed. "They can be an acquired taste. You can try them again some other time."

Because there would be so many other times. So many other chances to make up for the fact Theta had left her on Gallifrey. So many other chances to prove that she was someone he should have come back to visit.

And so many other chances for him to prove why he couldn't.

-VII-

"How is this the best way to find places to go?" Iota asked, leaning back against the console of her brother's ship as he flickered through maps of various points in the universe. "Is it normally this random?"

"I don't typically let people see this point," he mumbled. "How else would you expect to find somewhere to go?"

"Don't you have a list somewhere of where you'd like to go?"

"That's no fun." He pulled back slightly, stilling on an image that Iota turned to inspect as well. "A temporal problem in early 21st century Earth. London, England."

The time was familiar to Iota, beyond merely being close to one of her brother's favorite places to visit. "That's when and where we went when we visited Earth in the Academy."

Theta checked something. "There's no sign of another TARDIS's presence at that time."

"We would have been shielded from other TARDISes."

He looked at her. "But not from you?"

"Hopefully, if it is the same time." She studied the map. "Is that where you want to go? To see what the temporal problem is?" She frowned. "What even is a temporal problem? That sounds like something Koschei would be talking about, not you."

"Just because I didn't study it in the Academy, doesn't mean I don't know about it. I've learned a lot of things over the centuries."

Iota blinked. "How old are you? In Gallifreyan years."

"About nine hundred. What about you?"

She shrugged. "I have no idea."

That made him frown. "You don't know? How can you not know?"

"I never bothered to keep track." She blinked again. "What if I'm older than you now? Would I still be your little sister?"

He made a face. "You cannot be my older sister."

"Why not? I'd make a wonderful older sister." She crossed her arms. "You're about nine hundred? I'm two years younger. Eight hundred and ninety-eight." Theta's gaze flickered to the blaster still strapped to her leg. She knew what he thought, even without their mental bond. "Let's go solve the temporal problem. I want to see where my practical knowledge on the subject lies."

Again, he looked to the blaster. "No shooting anyone."

"Does anyone include walls?" When he looked at her, she shrugged. "What if we get trapped? Currently, that's the only setting I know how to use."

"Walls are fine. For now."

"Glad we agree." She pushed her brother away from the console. "Now, let me pilot us there."

"I can't help?"

"No, you cannot." She smiled. "Big sister orders."

Theta stepped back and watched as Iota focused. She could feel his attention, even without their mental bond.

"Do you regret it?"

"Regret what?"

"Saving me."

That time, Theta grabbed her arm and turned her to look at him, eyes narrowing. "Iota..."

"You think I'm a child, you didn't think I was worth visiting. Why would you think that saving me, being stuck with me, was a good idea?"

"Because we're alone." He didn't let her turn back around. "And you're my sister."

"You were afraid."

He nodded. "Terribly."

"So was I." Iota stepped back and turned back to the console. "The blaster helps." When Theta said nothing, she returned to piloting.

-VII-

Iota was the one to find the dead human. Theta had gone ahead in the corridor, the bomb in hand, preparing to head up to the roof to destroy the relay device up there. Iota had been following him, but she spotted the man and stopped despite herself.

Dead humans looked remarkably like dead Time Lords. Iota wasn't certain if she liked that or not.

If the name tag was anything to go off of, this man's name was Wilson. Iota practiced saying it, ensuring that she could still speak English, even without the TARDIS nearby.

' _Iota_ ,' Theta called over their mental bond, making her step back.

' _Coming._ '

Her brother was waiting for her at the end of the corridor. Once she reached him, there was a clatter further along, as though multiple things were falling. Theta led the way slowly towards the sounds, ducking into what looked like a storage area.

Almost immediately, they spotted a human surrounded by the Autons the siblings were tracking. She looked young. Theta rushed forward and reached between the Auton, grabbing the girl's wrist to get her attention. "Run." Before she could speak again, he pulled, making the human follow.

Iota was left to lead the way back through the corridors, but thankfully she remembered how to find the lift. Theta shoved the woman in after her before turning to face the closing doors. One of the Autons stuck its arm through, trying to grab at them, but Theta just took hold and pulled until it came off.

The girl seemed more terrified of that than she had of the Autons trapping her. "You pulled his arm off."

"Yep," Theta nodded, holding up the hand. "Plastic."

"Very clever. Nice trick! Who were they then, students? Is this a student thing or what?"

Iota frowned. "Why would they be students?"

"I don't know."

"Well, you said it," Theta said, agreeing with his sister. "Why students?"

"'Cos to get that many people dressed up and being silly, they got to be students."

Theta nodded. "That makes sense. Well done."

"Thanks." The human looked relieved.

"They're not students."

She frowned at Theta. "Whoever they are, when Wilson finds them, he's going to call the police."

Iota started at the name. "Wilson?"

The girl nodded. "Chief electrician."

"Wilson's dead."

 **A/N: Why, look, I wonder who this lovely young human is...**

 **Notes on reviews:  
**

 _Purplestan: It definitely isn't, and it will be something Theta regrets saying for some time._


	6. Chapter 6

The girl made a face at Iota's statement. "That's just not funny. That's sick!"

Theta gestured them out of the lift, turning to the controls. "Hold on. Mind your eyes."

The girl shook her head. "I've had enough of this now." Theta soniced the controls. "Who are you, then? Who's that lot down there?" the siblings moved away from the lift. "I said, who are they?"

"They're made of plastic. Living plastic creatures. They're being controlled by a relay device in the roof, which would be a great big problem if I didn't have this." Theta held up the bomb. "So, me and her" he nodded towards Iota "are going to go up there and blow them up, and we might well die in the process, but don't worry about us. No, you go home." He gestured in the opposite direction. "Go on. Go and have your lovely beans on toast. Don't tell anyone about this, because if you do, you'll get them killed." Iota pulled open the door to the building again, letting her brother follow her in, but he paused, looking back at the human. "I'm the Doctor, by the way. This is my sister, the Singer. What's your name?"

"Rose."

"Nice to meet you, Rose. Run for your life!" With a grin, Theta ducked back into the store after his sister.

As they started to run, Iota frowned. The name Rose was familiar. She'd met other people named Rose, one of her cousins had chosen it as a title, but a human named Rose...she didn't know why, but she knew it.

-VII-

If being good at exploding things was positive, the siblings were very talented. Now, as a team, they could not only count the Villengard factory, but also a human department store. The only problem was that the explosion meant they lost any lead they could have had to find the source of the living plastic, which Theta named as the Nestene Consciousness. Apparently, he'd encountered them before.

Iota was beginning to doubt the efficacy of Academy teaching since she'd never heard of them. There were many things she'd never heard of before.

Of course, Theta had taken that moment to comment that she may have just forgotten, which had resulted in her reminding him that she had a sonic blaster and was not afraid to use it.

Though they weren't able to track the Nestene Consciousness, they were able to track a single bit of the plastic that was separate. It didn't have the same shielding as the source. They used Theta's sonic to do it, making their way to a section of human housing, which Theta called Powell Estate. Iota found the word choice strange.

She needed to refresh her knowledge of early twenty-first century English.

"The signal is..." Theta turned in a circle, studying his sonic, "here."

Iota frowned at the door. "Can I shoot it? I want to see how the gun handles human materials."

"No, you cannot." Theta crouched and tapped the cat flap, frowning when it didn't open. He soniced it, making a few screws fall out on the other side. Then he opened it, looking in to see if it was possible to spot whatever piece of plastic they were tracking.

Instead, he found Rose. The human immediately opened the door.

"What're you doing here?" Theta asked.

"I live here."

"Well, what do you do that for?"

The human frowned. "Because I do. I'm only at home because someone blew up my job."

"It must have been the wrong signal," Iota said, shaking her head. "Unless you're plastic?"

Theta tapped Rose's forehead. "No, bonehead. Bye, then."

"You two. Inside. Right now." Rose grabbed both of the siblings' jackets and pulled them into the flat.

"Who is it?" another woman called from further inside.

"It's about last night," Rose told her, releasing the siblings before an open doorway before continuing on into the flat. "They're part of the inquiry. Give us ten minutes."

The other woman, who looked similar to Rose, but older, frowned at them. Iota supposed they were related. Likely Rose's mother, since humans resembled their biological family. "She deserves compensation."

Theta nodded. "Oh, we're talking millions."

Iota moved forward, following Rose. The woman continued to speak to Theta behind her. "I'm in my dressing gown."

"Yes, you are."

"There is a strange man in my bedroom."

"Yes, there is."

"Well...anything could happen."

Theta shook his head. "No." He followed his sister, who was not successfully hiding her disgust at the idea of her brother being flirted with.

' _I had to spend the entire time at the Academy watching you flirt and worse. It's your turn now.'_

' _Please tell me that most people don't try to flirt with you.'_

"Don't mind the mess," Rose continued, moving into the kitchen. "Do you want coffees?"

Theta shrugged. "Might as well, thanks. Just milk."

"The same." Iota had never had human coffee before either, but she trusted her brother's tastes, at least for this.

"We should go to the police." Rose glanced over her shoulder. "Seriously. All of us."

Theta flicked through a magazine on the coffee table. "That won't last," he mumbled to Iota, "he's gay and she's an alien."

"I'm not blaming you, even if it was just some sort of joke that went wrong."

Theta picked up a book. "Hmm...sad ending."

"They said on the news they'd found a body."

Theta turned to the cover, showing Iota the name written there. "Rose Tyler." Iota blinked. A human named Rose was recognizable enough, but a human named Rose Tyler...how did she know that? Meanwhile, Theta turned, finding his reflection. "Ah, could've been worse." He made a face and flicked his ears. "Look at the ears."

"Told you."

"All the same," Rose continued to speak as though the siblings weren't saying anything, "he was nice. Nice bloke."

Iota picked up a pack of cards and tried to shuffle them, but she failed, sending the cards flying.

"Anyway, if we are going to go to the police, I want to know what I'm saying. I want one of you to explain everything."

Back at the front door, the cat flap rattled again. Theta glanced back at it. "What's that, then? You got a cat?"

"No."

Theta took a step back to the door, but before he got far a plastic hand launched itself at his throat. Immediately, Iota pulled out her sonic gun, flicked to the traditional sonic setting, and fired. She was very glad that she'd honed her aim during her time in the war. She hit the arm immediately. Granted, she didn't know what would happen if she hit Theta with the sonic setting, but she was glad they didn't have to test it just then.

By the time Rose emerged with her mugs of coffee, Theta was holding a stiff arm. Rose froze, looking between Iota's weapon and the arm. "What the hell?" The fingers flexed on their own and attempted to go for Rose's face, but Iota shot it again. Rose only spilled a little of the coffee, though it landed on the mess on the table. "You have a gun?"

"Yes." She lowered it.

Theta picked up the arm again, wiggling it. "It's all right, that's stopped it. There you go, you see? Armless."

Iota sighed.

The siblings exchanged a look and moved out of the apartment again. Rose, after putting down the mugs, rushed after them. "Hold on a minute. You two can't just go swanning off."

"yes, we can. Here we are. This is us, swanning off." Theta gave a little wave. "See you."

"But that arm was moving. It tried to kill me."

Iota frowned. "It didn't even touch you."

"It still tried!"

Theta pointed at the human. "Ten out of ten for observation." In unison, the siblings turned, walking away again.

"You can't just walk away," Rose said again. "That's not fair. You've got to tell me what's going on."

"Life's not fair," Iota said, the first out of the staircase and back towards where they'd left the TARDIS.

Behind them, Rose was not being denied. Iota was almost impressed. "All right, then. I'll go to the police. I'll tell everyone. You said, if I did that, I'd get people killed." She put her hands on her hips. "So, your choice. Tell me, or I'll start talking."

Theta crossed his arms. "Is that supposed to sound tough?"

"Sort of."

"Doesn't work."

Rose looked between them. "Who are you?"

"Told you. She's the Singer, I'm the Doctor."

"Yeah, but Doctor what?" Iota resisted the urge to be annoyed at the fact Rose was fixating on Theta and his odd name.

"Just the Doctor." He nodded at Iota. "And she's just the Singer."

"The Doctor. And the Singer."

Theta gave a little wave. "Hello!"

"Is that supposed to sound impressive?"

"Sort of," Theta said, at the same time Iota nodded with a, "yes!"

That, if anything made Rose crack a small smile. Iota wondered if the human had any siblings. "Come on, then. You can tell me. I've seen enough. Are you two the police?"

"No, we were just passing through. We're a long way from home."

"But what have I done wrong? How comes those plastic things keep coming after me?"

Theta waved a hand. "Oh, suddenly the entire world revolves around you. You were just an accident. You got in the way, that's all."

"It tried to kill me."

"It was after us, not you." Theta gestured between the siblings. "Last night, in the shop, we were there, you blundered in, almost ruined the whole thing. This morning, we were tracking it down, it was tracking us down. The only reason it fixed on you is 'cos you've met us."

Rose raised her eyebrows. "So what you're saying is, the entire world revolves around you two."

Theta cracked a small smile. "Sort of, yeah."

"You're full of it."

"Sort of, yeah."

"But, all this plastic stuff. Who else knows about it?"

Theta shook his head. "No one."

"What, you two are on your own?"

"Well, who else is there?" Theta gestured at the space around them. "I mean, you lot, all you do is eat chips, go to bed, and watch telly, while all the time, underneath you, there's a war going on." Iota had to look down at that. Before the war, even at the very beginning of it...that had been her. She'd been living that exact life on Gallifrey. And she'd been happy not caring.

Rose noticed Iota's reaction. "Okay. Start from the beginning. I mean, if we're going to go with the living plastic, and I don't even believe that, but if we do, how do you kill it?"

"The thing controlling it projects life into the arm." Theta waved the arm. "When the Singer shot it, it cut off the signal, dead."

"So that's radio control?"

"Thought control," Iota corrected, having had Theta explain it to her thoroughly before they'd gone out searching.

Theta looked the human over when she remained silent. "Are you all right?"

"Yeah. So, who's controlling it, then?"

"Long story."

"But what's it all for? I mean, shop window dummies, what's that about? Is someone trying to take over Britain's shops?"

"No."

The human frowned. "No."

"It's not a price war. They want to overthrow the human race and destroy you." The human was silent again. "Do you believe us?"

"No."

That time, it was Iota's turn to frown. "But you're still listening."

The human looked between them again. "Really, though. Doctor. Singer. Tell me, who are you?"

Theta glanced at Iota, but he was the one to speak. "Do you know like we were saying about the Earth revolving? It's like when you were a kid. The first time they tell you the world's turning and you just can't quite believe it because everything looks like it's standing still. I can feel it. The turn of the Earth. The ground beneath our feet is spinning at a thousand miles an hour, and the entire planet is hurtling round the sun at sixty-seven thousand miles an hour, and I can feel it. We both can feel it. We're falling through space, the three of us, clinging to the skin of this tiny little world, and if we let go..." Iota wondered if Theta was going to reach for her hand, but he didn't move. "That's who we are. Now, forget us, Rose Tyler. Go home."

Without another word, Theta turned and walked back to the TARDIS. Iota followed after another breath, her lids fluttering closed.

She'd never really noticed how much she could feel about the state of the universe or the planet. She'd never really considered that other people, other species, couldn't feel the same thing. Never really considered the lives and fears and families of people who were not Gallifreyan.

Now she would be forced to because the only other Gallifreyan left was her big brother.

 **A/N: Hmm, I wonder where she's recognized Rose from...**

 **Notes on reviews:**

 _Purplestan: So am I :)_

 _Rosealyn: Oh, their first meeting in this universe will definitely be...interesting_


	7. Chapter 7

Theta didn't actually get a chance to explain to Iota what the signal he'd found meant before he rushed out of their TARDIS. They'd been trying to use the plastic arm that had tried to attack them in order to find the center of the Nestene Consciousness, but either Iota had damaged it when she shot it, or the signal wasn't strong enough. Theta was fairly certain it was the latter. The plastic was enough for Theta to perfect his anti-plastic – he already had a formula he'd used successfully in the past, but the new arm helped to ensure that it would work with the new kind of Earth plastic that the Nestene was using.

Iota had watched him work from the side. She didn't particularly regret not knowing much about this type of science, though she did wish that she could understand exactly what he was doing.

They'd been trying to use the TARDIS to find anything else that had survived the explosion, since their efforts to find the main consciousness were for naught, when Theta just turned and ran from the ship.

She was left only with the vague knowledge of Rose and immediate danger. She was very tempted to follow him regardless – he didn't get to protect her – but she decided that, if they really were in any immediate danger, it would be better to be able to bring the TARDIS directly to him to rescue.

Thus, when Theta and Rose ran inside the ship, one much more panicked than the other, she was already at the console. The fact her brother was holding what looked to be a plastic head did not shock her. If anything, it made her hopeful. A head would be much better for tracking than an arm.

"It's going to follow us!" Rose cried, and Iota got the sense that the 'it' was one of the plastic creatures they were tracking. Theta helped to confirm that through the mental bond.

Theta waved a hand. "The assembled hordes of Genghis Khan couldn't get through that door, and believe me, they've tried." Iota's eyes widened at that. _'I'll tell you later_.'

' _You'd better._ '

Theta flashed her a smile before focusing on Rose again. "Where do you want to start?"

Rose looked to the side, taking in the scope of the room and no doubt comparing it to the size of the outside. Iota understood, from Theta and the few records of non-Gallifreyans entering TARDIS's she'd read over the centuries, that it was quite disorientating. Most other species in the universe couldn't grasp the extreme difference in size.

Iota thought that was rather small-minded of most of the universe.

"Er...the inside's bigger than the outside?" Rose started to walk up to the console, leaving the Doctor to follow her, resting the plastic head on the console beside Iota once he reached her.

Iota turned, attaching the electrodes to the head. Theta had previously needed to explain exactly how it worked, but since it had to do with the TARDIS, even if it wasn't her true area of expertise, she took charge. "Yes."

"It's alien."

"Yes."

Rose's eyes widened. "Are you two aliens?"

"I would have thought..." but Theta cut her off.

"Yes. Is that all right?"

It took Rose a second, but she still nodded. "Yeah."

"The ship is called the TARDIS," Iota provided, guessing that her brother hadn't bothered to explain anything before leading the human inside. "Stands for Time and Relative Dimension In Space."

After a moment, Rose burst into tears. Immediately, Theta rushed forward, almost looking ready to touch Rose to comfort her, but he didn't get that close. "That's okay. Culture shock. Happens to the best of us."

"Did they kill him?" Rose asked, still crying. "Mickey? Did they kill Mickey? Is he dead?"

Theta blinked. "Oh. I didn't think of that."

"He's my boyfriend. You pulled off his head. They copied him and you didn't even think? And now you're just going to let him melt?"

"Melt?" both siblings turned to look at the console and found that the head had, indeed, begun to melt. "Oh, no, no, no, no, no!"

They rushed to set the TARDIS in flight again, Iota not even bothering to tell Theta not to help. Rose scrambled for purchase. "What're you doing?"

"Following the signal," Theta explained. "It's fading." He frowned, moving to the scanner. "Wait a minute, I've got it...no, no, no, no, no, no, no, no! Almost there...almost there...here we go!" the TARDIS landed with a small thud, with Theta having taken charge of the landing. The siblings rushed for the door.

"You can't go out there," Rose tried, following them. "It's not safe."

Sadly, it turned out that it was very much safe outside. They were on the bank of the Thames with no sign of the Nestene Consciousness in sight. Theta turned in a circle, looking around. "We lost the signal. We got so close."

Rose looked around, stumbling slightly in place. It occurred to Iota that she had not expected them to move, though that felt rather stupid to her, as the siblings had quite obviously done something to the TARDIS. "We've moved. Does it fly?"

Iota frowned, trying to think of a way to explain it to a human. "It...disappears there and reappears here." She shook her head. "You wouldn't understand."

"If we're somewhere else, what about that headless thing? It's still on the loose."

Theta shook his head. "It melted with the head." He faced the human. "Are you going to witter on all night?"

"I'll have to tell his mother." When the siblings said nothing, Rose sighed. "Mickey. I'll have to tell his mother he's dead, and you both just went and forgot him, again!" She shook her head. "You were right, you are alien."

"Look, if we did forget some kid called Mickey..."

"Yeah, he's not a kid."

"It's because we're trying to save the life of every stupid ape blundering on top of this planet, all right?"

Rose nodded. "All right."

"Yes, it is!"

Rose crossed her arms. "If you're aliens, and siblings, how comes you" she focused on Theta "sound like you're from the North?" Iota laughed at that, which only made Theta pout more.

"Lots of planets have a north."

Rose looked back at the TARDIS. "What's a police public call box?"

"It's a telephone box from the 1950s. It's a disguise."

"Okay. And this...this living plastic. What's it got against us?"

Theta crossed his arms. "Nothing. It loves you. You've got such a good planet. Lots of smoke and oil, plenty of toxins and dioxins in the air, perfect. Just what the Nestene Consciousness needs. Its food stock was destroyed in the war, all its protein plants rotted, so Earth," he gestured at the city, "dinner!"

"Any way of stopping it?"

Theta pulled a vial from his jacket. "Anti-plastic."

"Anti-plastic."

"Anti-plastic. But first, we've got to find it." Theta turned to face the city. "How can you hide something that big in a city this small?"

"Hold on. Hide what?"

"The transmitter." Theta moved to stand beside Iota, trying to see if she had an any better view of the city, though she still saw nothing that looked like what Theta had described. "The Consciousness is controlling every single piece of plastic, so it needs a transmitter to boost the signal."

"What's it look like?"

"Like a transmitter. Round and massive, slap bang in the middle of London." Theta spread his arms to encompass the city. "A huge circular metal structure like a dish, like a wheel. Radial. Close to where we're standing. Most be completely invisible." He turned, looking to Rose, and frowned. "What?" Rose said nothing. "What?" He turned to try to follow Rose's gaze but saw nothing remarkable. Iota did the same, as unsuccessful as her brother. "What? What is it? What?"

With a blink, Theta seemed to realize something and Iota was even more annoyed that she didn't know.

Thankfully, their mental bond worked.

"Oh..." Theta grinned, staring at the London Eye, which Iota decided, at that moment, she hated very much. She'd heard about it before from textbooks on Gallifrey, even thought it was rather impressive, but now she thought the complete opposite. It was stupid. Stupid and big and something they shouldn't have missed! "Fantastic!"

"That is almost too stupid to be real," Iota mumbled.

"Too stupid to be real is my favorite type of thing," Theta said.

Iota shoved him for that.

Rose looked between them. "Are you two really siblings? Like, biologically?"

"Biological little sister." Theta started to move back. "We can explain more later. Now, we need to get after the Nestene Consciousness. Want to come?" Rose grinned at that and, together, the newly made trio began to run towards the London Eye.

"What is the Nestene Consciousness anyways?"

"Think of it, plastic all over the world, every artificial thing waiting to come alive. The shop window dummies, the phones, the wires, the cables..."

"The breast implants."

Theta shrugged. "Still, we've found the transmitter. The Consciousness must be somewhere underneath." He gestured beneath the London Eye.

"What about down here?" Rose paused at a wall as they reached it, pointing down to a manhole entrance with steps leading to it.

Iota eyed it. "Looks promising." She led the way down and, before Theta could use his sonic, shot the entrance with the squareness function. It was very satisfying.

"What is that?" Rose asked her.

"A sonic blaster." Iota kept it out. "Brother disapproves."

"Of course I disapprove," Theta mumbled. "You can't just shoot the Nestene Consciousness."

"Then it's good I'm not planning on doing that." Iota glanced back at Rose. "This isn't a real weapon. Close to one, but not exactly." Though Iota liked having a blaster in her hand, liked how it made her safe, she didn't like harming people. She'd had enough with hurting in the war. Instead, she was just keeping it to maintain her own safety.

Though, before Theta had made it clear that the anti-plastic was the best option for defeating the Nestene Consciousness, she had considered what shooting it would do. If she would have been fine with that. And while she'd never told her brother that she'd considered it, questioned it, she knew the answer.

Iota did not like shooting people – or any other sentient creatures. But she liked making people think she could. Liked to have that option.

Even if it made Theta uncomfortable, Iota was not going to stop carrying her sonic blaster.

 **A/N: Just good old brother and sister and Rose adventuring :)**

 **Notes on reviews:**

 _Purplestan: Those episodes will be interesting...and not just because Iota and Jack will be able to compare sonic blasters ;)_


	8. Chapter 8

They were very careful as they moved down further towards the Nestene Consciousness. Iota still led the way, with Rose behind her and Theta at the back. Her brother seemed to have quite a difficult time not forcing Iota to move behind him, but she felt the weapon in her hand helped convince him that she was a good leader.

She climbed down a ladder and turned, eyes widening at the sight. Theta had explained what they were looking for, given her the rough image, but it was different seeing the consciousness in person. Iota went down another staircase to be closer, but she did stop there, leaning on the railing and looking down. Theta and Rose were close behind.

"The Nestene Consciousness," Theta introduced. "That's it, inside the vat. A little plastic creature."

"Well, then. Tip in your anti-plastic and let's go."

Theta glanced at Rose. "Sis and I aren't here to kill it. I've got to give it a chance." He moved past Iota to a level below them, better to see the Nestene Consciousness. It was clear that he intended Iota and Rose to stay behind, but neither woman stayed in place. "I seek audience with the Nestene Consciousness under peaceful contract according to convention 15 of the Shadow Proclamation." The Consciousness seemed to flex. Iota vaguely understood the response, though she felt she only understood that because of her mental bond with Theta rather than any personal knowledge of the Consciousness's language. "Thank you. If I might have permission to approach?"

Rose, seeing something, rushed past Iota and down the stairs. Theta rolled his eyes at the sight before beginning to make his own way down the stairs.

"Oh, God! Mickey, it's me!" Rose cried. "It's okay. It's all right."

The young male human, hunched on a lower level, grabbed at Rose. "That thing down there, the liquid. Rose, it can talk!"

"You're stinking." Rose looked up at Theta as he passed her. "Doctor, they kept him alive."

"Yeah, that was always a possibility. Keep him alive to maintain the copy."

"You knew that and you never said?"

"Can we keep the domestics outside, thank you?"

Rose looked up to Iota. "You never said?"

"I had no idea that there was a chance that he survived."

Theta reached the bottom. Iota moved more to the railing, leaning against it to see him properly. "Am I addressing the Consciousness?" Another flex, close to a roar. "Thank you. If I might observe, you infiltrated this civilization by means of warp shunt technology. So, may I suggest, with the greatest respect, that you shunt off?" The Consciousness roared again. "Oh, don't give me that. It's an invasion, plain and simple." He frowned. "Don't talk about constitutional rights. I am talking!" the Consciousness quieted, but only slightly. "This planet is just starting. These stupid little people have only just learnt how to walk, but they're capable of so much more. I'm asking you on their behalf. Please, just go."

' _Theta!'_ Iota shouted at the same time Rose called out, "Doctor!"

Two animated plastic Autons grabbed Theta. Iota managed to shoot one of them – she wasn't shooting to kill, only to shock – but before she could hit the other one, it reached into his pocket and pulled out the anti-plastic.

"That was just insurance," Theta tried. "I wasn't going to use it. I was not attacking you." He looked up at Iota. "Despite what she just did."

"It was self-defense!"

"You weren't being attacked!" Theta looked back to the Consciousness. "We're here to help. We are not your enemy. I swear, I'm not." The Consciousness roared. "What do you mean?"

Below Iota, a door slid open, revealing the TARDIS. It took all of Iota's self-control – which was quickly dwindling – not to shoot the consciousness for daring to threaten the last TARDIS.

"No," Theta gasped. "Oh, no. Honestly, no. Yes, that's my ship." Another roar. "That's not true. I should know, I was there. I fought in the war. It wasn't my fault. I couldn't save your world! I couldn't save any of them!"

Iota hadn't even thought that the Nestene Consciousness could have been affected by the war. To her, the war had been Time Lords against the Daleks. The rest of the universe, all the other planets it had affected...she'd never bothered to give them a thought. Even after the war was ended.

She knew that she hadn't been personally responsible for any of the other planets that had been destroyed. She'd been a soldier stuck on Gallifrey, likely because the other Time Lords hadn't trusted her to go off planet when she was the sister of a criminal and wife of a madman.

And Theta had stopped it. He'd ended the war. Yes, the Nestene Consciousness's planet had been destroyed before then, but he'd stopped the same from happening to others!

"What's it doing?" Rose asked, not seeming to know which sibling she should ask.

"It's the TARDIS! The Nestene's identified its superior technology. It's terrified." More roars and the Consciousness rolled, fighting at its binds. "It's going to the final phase. It's starting the invasion! Get out, Rose! Just leg it now!"

' _What do I do?'_ Iota asked, wishing she'd made Theta give her another vial of the anti-plastic.

The Consciousness began bursting with energy bolts. One nearly struck Iota, making her stumble back. "It's the activation signal," she recognized. "It's transmitting!"

"Get out, Rose!" Theta tried again. "Just get out! Run!"

"The stairs have gone." Iota looked down to find that, indeed, the human couldn't leave the room, though she could come up the stairs closer to the TARDIS and Iota above it.

"Get them out, Singer!" Theta called as the Auton still holding Theta began to drag him towards the vat.

"Follow me!" Iota told the humans, moving to the TARDIS. She opened it by touching the lock and, almost immediately after he reached her, Mickey ran inside. He didn't even seem overly bothered that it was bigger on the inside.

Rose paused at Iota's side. "He's going to die!"

"No!" Theta tried, fighting back against the Auton.

"Time Lord," the Nestene Consciousness hissed.

Rose ran from Iota and around the room, looking for something. "Just get safe!" Iota shouted at the human. "There's nothing you can do!"

Rose shook her head. The human didn't seem willing to listen to Iota. She mumbled something to herself and grabbed an ax. "But I tell you what I have got." That time, she spoke loud enough that Iota could hear her. "Jericho Street Junior School under 7s gymnastic team. I've got the bronze!"

Iota guessed what Rose was planning and shot the rope holding the chain before the human could cut it with the ax, allowing the human to start quicker. Rose grabbed the chain and swung out over the Nestene Consciousness, kicking two of the Autons into the Consciousness. One of the Autons was the one holding Theta's anti-plastic and, when it hit the Consciousness, the creature began to turn blue.

"Rose!" Theta shouted and he reached out for Rose as the human swung close to him again, forcing her to stop with a stumble.

"Get up here, now!" Iota called down to them both, moving back towards the TARDIS. Her brother did not fight her. Explosions began around them, the entire structure beginning to collapse, and by the time Theta and Rose had reached the TARDIS Iota was already piloting them away and back up to the surface.

The TARDIS's song swelled in anger at having been transported without permission, but thankfully Iota could still control her.

They landed back on the embankment and Mickey, who'd been clinging to one of the supports, ran out looking slightly sick. Rose pulled out her phone and followed Mickey. Iota and Theta followed slowly, though Theta stopped in the doorway of the ship and Iota behind him.

Rose looked back towards Theta and Iota. "A fat lot of good you were."

"Oi, I shot a few things."

Theta flashed a grin back at Iota before shrugging. "Nestene Consciousness? Easy."

"You were useless in there," Rose fixed her focus on Theta. "You'd be dead if it wasn't for me. And your sister."

"Mainly you," Iota conceded. Rose hadn't actually needed Iota's assistance to accomplish what she'd done.

Theta's expression hardened. Iota knew it through their bond, even if she couldn't properly see him at that moment. "Yes, I would. Thank you." He nodded. "Right then, sis and I'll be off...unless...er..." Theta glanced back at Iota and she knew what he would ask.

She hadn't actually thought about the fact her brother liked taking companions, as he'd termed them. She hadn't considered what would happen when they met someone her brother liked enough to want to travel with him. Someone who would impede on the siblings' and their carefully sculpted repairing relationship.

Iota hadn't told Theta so many things. They were still basically strangers. So many secrets still hung between them. So many moments of tension.

And Theta wanted to bring someone else into that.

She supposed she should have expected that. She couldn't have honestly thought that her brother would want to stay alone with her for eternity. But she had hoped they would get a little bit longer together. After everything that had happened, she needed a little more time with him.

' _Theta...it's so soon.'_

' _It might help. Someone separate from the situation, to help us process.'_

' _And someone to give me an example of how you want me to see the universe?'_

' _Just for a little. One trip. Just to try it. Who knows. Maybe you'll like it.'_

Iota looked back at Rose. For the humans, their conversation was lasting barely a second. And then she remembered, in a burst, how she knew the name Rose Tyler.

When Theta and she had first formed their mental bond and she'd walked through his mind, there had been doors and a fountain with names intermingled with all the stars of the universe. This human, this random young blonde human, was important to Theta. Would always be and had always been, even before they'd ever met. _'Alright.'_

"...I don't know, you could come with us," Theta finished, looking back to Rose. "This box isn't just a London hopper, you know. It goes anywhere in the universe free of charge."

Mickey grabbed at Rose. "Don't. They're aliens. They're...things."

"He's," Theta nodded at the human boy, "not invited." Back to Rose. "What do you think? You could stay here, fill your life with work and food and sleep, or you could go anywhere."

Iota wondered what she would have said if Theta had ever offered her this choice on Gallifrey. She'd had wanderlust, but nowhere close to Theta or even Koschei.

"Is it always this dangerous?"

"Yeah."

Rose looked back at Mickey. "Yeah, I can't. I've...er...I've got to go and find my mum and someone's got to look after this stupid lump, so..."

"Okay." Theta nodded. "See you around." He stepped back into the TARDIS beside Iota. She was already back at the TARDIS, sending them into the vortex, but she watched her brother in the process. He was looking down, more than slightly put out.

"You want to go back for her, don't you?"

Theta looked up at her. "You're sure you're okay with it?"

"Companions are important to you." She didn't bother waiting for Theta to speak his confirmation. "The point of this is that we will learn to understand each other better, Theta."

"Is that the point?"

"I want to understand you and your universe."

Theta nodded. "Thank you."

She pointed at him as she began to pilot them back to Rose Tyler. "I expect more thanks for this. This is a big sacrifice for a little sister to make."

"What? Sharing me?"

"No, you idiot. Sharing the TARDIS." Iota stroked a bit of the console. "She's a better sibling than you ever were." As if she agreed, Theta's TARDIS's song rose, making Iota smile.

The ship settled back on Earth smoothly. Immediately, Theta turned and went for the door, leaning out of it. "By the way," he called out to where Rose and Mickey were still standing, though Mickey, somehow, looked even worse, "did I mention it also travels in time?"

Rose's eyes widened and Iota knew that sentence had sealed her fate. "Thanks," Rose told Mickey, glancing back at him.

The human shook his head. "Thanks for what?"

"Exactly." Rose kissed Mickey's cheek and stood from him. With a short breath, she ran towards the TARDIS.

And Iota, despite herself, actually felt excited at their future.

 **A/N: Rose is an official companion! Was tempted to not have the Doctor take her on just yet, but Iota liked Rose enough that I couldn't see her stopping her brother :)**

 **Notes on reviews:**

 _lautaro04: Was tempted for her to shoot it just for the heck of it, but I decided Theta would have been very careful to tell her NOT to do that ;)_

 _Purplestan: I've always seen the twins as essentially fixed points in time given their prophetic and empathic abilities, so, yes, they will exist in this universe in some form :) The Master doesn't know about her Gallifreyan pregnancy. In this universe, she hasn't actually seen him since the conception._


	9. Chapter 9

Rose came to a stop at the TARDIS console beside Iota, but opposite Theta. "Right then, Rose Tyler, you tell us," Theta told the human, grinning at her. "Where do you want to go? Backwards or forwards in time. It's your choice. What's it going to be?"

She considered it for a moment. "Forwards."

"How far?" Iota asked, already moving to set the TARDIS into motion.

"One hundred years."

Theta stepped up to help direct the TARDIS to a location he had in mind and there were a few seconds of travel before the TARDIS settled. "There you go. Step outside those doors, it's the twenty-second century."

Rose glanced back at the door. "You're kidding."

Theta shrugged. "That's a bit boring, though. Do you want to go further?"

Rose grinned at that. "Fine by me."

Theta exchanged a look with Iota and they set the TARDIS into motion again. Rose seemed mesmerized by the siblings' ability to work together. "Ten thousand years in the future. Step outside, it's the year 12005, the new Roman Empire."

Rose let out a breath close to a laugh, shaking her head. "You think you're so impressive."

"I am so impressive."

"You wish."

In clear view of the other two, Iota made a face that made Rose laugh.

"Right then," Theta said, "you asked for it. I know exactly where to go. Hold on!" That time, he began to pilot them so quickly that Iota was nearly thrown from the console and had to focus to actually keep them steady.

Thankfully, Rose actually listened to Theta's warning and clung to the console.

' _Stop showing off!'_

Theta flashed a grin at Iota. _'Come on, sis. Don't ruin the fun!'_

After being flung through the time vortex, the TARDIS settled. Rose waited a moment before stepping back from the console. "Where are we? What's out there?"

Theta only nodded at the door. Rose turned and ran for it. She left the door open as she left, which made Iota realize she would need to have a talk with the human about closing the TARDIS doors. This ship, this beautiful thing, was the last TARDIS left. They had to treat her with respect.

Theta and Iota followed the human at a slower pace, but even Iota started to pick up her pace when she saw where they'd landed.

They were in a gallery of sorts with a perfect view of the Earth and the sun beyond. Something about the sight pulled on Iota's hearts. It reminded her of when they'd gone to see the birth and death of a star with her Year at the Academy, but it wasn't just that.

"You know," Theta said, stopping beside Rose, "you spend all your time thinking about dying, like you're going to get killed by eggs or beef or global warming or asteroids. But you never take time to imagine the impossible, that maybe you survive. This is the year five point five slash apple slash twenty-six. Five billion years in your future and this is the day..." Theta glanced at his watch, "hold on." The sun flared, darkening into a redder color. "This is the day the Sun expands. Welcome to the end of the world."

Iota reached out and touched the glass and didn't know quite why. She'd seen the expansion and death of a star before and part of her knew that was all that was happening now.

"Shuttles five and six now docking," a computer announced. "Guests are reminded that Platform One forbids the use of weapons, teleportation, and religion. Earth Death is scheduled for fifteen thirty-nine followed by drinks in the Manchester Suite."

Theta touched Rose's shoulder and pulled her away from the window, but he didn't reach for Iota. It was only after Theta and Rose had stepped away that he realized his little sister wasn't with them and turned back. _'Iota...'_

She made herself turn away and was glad when she realized she didn't actually have tears in her eyes, though she felt she was close to that point. She followed Theta and Rose silently, touching Koschei's ring.

"So, when it says guests, does that mean people?" Rose asked Theta.

"Depends what you mean by people."

The human seemed confused. How small must the universe be to her? "I mean people. What do you mean?"

"Aliens."

"What are they doing on board this spaceship? What's it all for?"

"It's not really a spaceship, more like an observation deck. The great and the good are gathering to watch the planet burn." Theta stopped at a wall panel for a door and soniced it.

"What for?"

"Fun." The door slid open. The next room was clearly intended as an observation deck. It was large, full of a few display cases and had a much better view of the soon to be planet death. "Mind you, when I said the great and the good, what I mean is, the rich."

Rose shook her head. "But, hold on. They did this once on Newsround Extra. The sun expanding, that takes hundreds of years."

"Millions, but the planet's now property of the National Trust. They've been keeping it preserved. See down there?" Theta gestured at the large window. "Gravity satellites holding back the sun."

"The planet looks the same as ever. I thought the continents shifted and things."

"They did, and the Trust shifted them back." Iota glanced at Theta as he explained. She knew none of this. They'd gone to the same Academy and, even if she hadn't been paying as much attention to the history of other planet's as he had, she'd been roommates with someone who'd practically dedicated her life to learning. Iota should have retained some of this. But she didn't recognize almost everything he said. "That's a classic Earth. But now the money's run out, nature takes over."

"How long is left?" Iota asked him.

"About half an hour and then the planet gets roasted."

"Is that why we're here?" Rose said. "I mean, is that what you do? Jump in at the last minute and save the Earth?"

Theta put his hands into his pockets. "We're not saving it. Times up."

"But what about the people?"

Iota frowned at the planet. "It's empty. They're all gone." She remembered that, at least. She knew that humanity had left Earth long ago.

Rose nodded. "Just me, then."

"Who the hell are you?" someone shouted, making the trio turn. They were rushing towards the trio, eyes narrowed, and dressed in Iota's best guess at a servant's uniform.

"Oh, that's nice, thanks," Theta said, moving to step slightly in the way of the two women, though Iota didn't let that stand. She touched her sonic blaster as she moved beside him.

"But how did you get in?" the alien looked them over. "This is a maximum hospitality zone. The guests have disembarked. They're on their way any second now."

"That's me." Theta nodded. "I'm a guest. Look, I've got an invitation." He pulled out his psychic paper, showing the alien. "Look. There, you see? It's fine, you see? The Doctor, plus two. I'm the Doctor, this is Rose Tyler, and this is my sister, the Singer, and this is Rose Tyler. They're both my plus one. Is that all right?" he put the paper away again.

The alien blinked. "Well, obviously. Apologies, et cetera. If you're on board, we'd better start." They bowed and stepped back, moving towards a lectern. Iota forced herself to move her hand off her blaster. "Enjoy."

Rose frowned at Theta. "The paper's slightly psychic. It shows them whatever I want them to see. Saves a lot of time."

Rose glanced back to the alien. "He's blue."

Theta nodded. "Yeah."

"Okay."

The alien smiled at the trio. "We have in attendance the Doctor, the Singer, and Rose Tyler. Thank you. All staff to their positions." The alien clapped and more similar looking aliens rushed into the room. "Hurry, now, thank you. Quick as we can. Come along, come along." Again, a smile to the trio. "And now, might I introduce the next honored guest? Representing the Forest of Cheam, we have trees, namely Jabe, Lute, and Coffa." A woman, accompanied by two men, entered. All three of them looked made of wood. "There will be an exchange of gifts representing peace. If you could keep the room circulating, thank you."

' _Time to see how good you are at socializing.'_

Iota watched the representatives of the Forest of Cheam move through the room. _'I don't know what to do. I didn't even know there was a Forest of Cheam.'_

' _It's alright. You can learn.'_

"Next, from the solicitors Jolco and Jolco, we have the Moxx of Balhoon." Another alien, blue and mainly a head and body in a remote-controlled transport chair, entered. "And next, from Financial Family Seven, we have the Adherents of the Repeated Meme." A group of black-robed aliens entered, not quite humanoid. "The inventors of Hypo-slip Travel Systems, the brothers Hop Pyleen. Thank you." Reptilian-esque aliens dressed in furs entered.

As the announcements continued, the representatives of the Forest of Cheam stepped up to the trio. "The Gift of Peace," the woman said. "I bring you a cutting of my Grandfather." She gave Theta a twig in a pot.

Theta accepted it as carefully as he could. "Thank you. Yes, gifts. Er...I give you in return air from my lungs." He leaned forward and breathed on the woman.

She blinked. "How intimate."

"There's more where that came from."

The woman smiled, lowering her voice slightly. "I bet there is."

' _You're doing this to amuse me, aren't you?'_

' _Not just you.'_

Another of the aliens approached the trio. "The Moxx of Balhoon," Theta greeted, and Iota was thankful for that since she had no idea which of the aliens that had been introduced this was. She'd never enjoyed large societal events, even when just surrounded by Gallifreyans or her family.

"My felicitations on this historical happenstance. I give you the gift of bodily salivas." The alien spit, hitting Rose in the face.

Theta smiled at him. "Thank you very much." The black-roped aliens were next. "Ah! The Adherents of the Repeated Meme. I bring you air from my lungs." Theta breathed again.

An Adherent held out a metallic ball. "A gift of peace in all good faith." Rose took it carefully, exchanging a look with Iota that she didn't truly expect to share, but she did. It was clear that Rose was as uncomfortable as Iota was.

"And last but not least, our very special guest. Ladies and gentlemen, and trees and multiforms, consider the Earth below. In memory of this dying world, we call forth the last Human. The Lady Cassandra O'Brien Dot Delta Seventeen."

What entered was merely skin stretched onto a form, accompanied by two aides. Iota could just about see facial features. Somewhere in the back of her memory, she remembered mentions of the last human named Cassandra, but she didn't remember anyone mentioning the last human was a sheet of skin. "Oh, now, don't stare," Cassandra said, looking around the room. "I know, I know it's shocking, isn't it? I've had my chin completely taken away and look at the difference. Look how thin I am. Thin and dainty. I don't look a day over two thousand. Moisturize me," she told an aide. "Moisturize me."

The aide did so, using a spray pump. "Truly, I am the last Human. My father was a Texan, my mother was from the Arctic Desert. They were born on the Earth and were the last to be buried in its soil. I have come to honor them and say goodbye." Something watered at the corners of her eyes. "Oh, no tears, no tears." One of the aides wiped her eyes for her. "I'm sorry. But behold, I bring gifts. From Earth itself, the last remaining ostrich egg." One of the ship's blue aliens came forward, carefully holding out the egg. "Legend says it had a wingspan of fifty feet and blew fire from its nostrils." Iota frowned. She didn't know much about Earth ostriches, but she didn't remember fire breathing from any point in its evolution. "Or was that my third husband?" A few of the gathered laughed. "Oh, no. Oh, don't laugh. I get laughter lines. And here, another rarity."

Slowly, Rose moved forward to walk around Cassandra. More of the ship's staff brought in some type of Earth music device. Iota vaguely recognized it from the choirs of Gallifrey. "According to the archives, this was called an iPod. It stores classical music from humanity's greatest composers. Play on!" One of the staff members hit a button, beginning to play a song.

"Refreshments will now be served. Earth Death in thirty minutes."

Rose looked back to Iota, shook her head, and ran from the room. It actually shocked Iota when she immediately moved to follow the human.

' _What are you doing?'_

Iota took a breath. She wasn't panicking, not in the same way she knew Rose was, but all of this... _'I need a break. I'll keep her safe.'_

And then she left her brother to follow a young human girl.

 **A/N: Some of Iota's first real interactions with other alien races here.**

 **Notes on reviews:**

 _Purplestan: No problem, I love answering questions :)_


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